Apparently Luke Skywalker was not Master Yoda's last student, as artist Lawrence Noble's first time meeting with Yoda lead him to numereous collaborations with Lucasfilm. He says the first time he saw him on the screen was "intoxicating"; and that experience led him to sculpting, which he had never done before. A few years later, he made three bronzes based on an eight inch tall sculpt of Yoda. One of the bronzes went to an avid Star Wars art collector, who invited Noble to dinner, along with artists Ralph McQuarrie and Drew Struzan. The 10th Anniversary of The Empire Strikes Back led to a commemorative poster, as well as, a limited edition Yoda bronze produced by the Official Star Wars Fan Club.
Another collector led Noble to sculpt a full-size Yoda; one of which he presented to George Lucas at Skywalker Ranch, one topped a fountain at Lucasfilm's Presidio Headquarters, one was donated last year the opening of Lucasfilm’s new Sandcrawler building in Singapore.
(Source: The Official Star Wars Blog)